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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012-2022 OpenVPN Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License Version 3
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
#ifndef OPENVPN_COMMON_PERSISTFILE_H
#define OPENVPN_COMMON_PERSISTFILE_H
#include <sys/types.h> // for open(), lseek(), ftruncate()
#include <sys/stat.h> // for open()
#include <fcntl.h> // for open()
#include <unistd.h> // for write(), lseek(), ftruncate()
#include <errno.h>
#include <string>
#include <openvpn/common/size.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/scoped_fd.hpp>
#include <openvpn/common/write.hpp>
#include <openvpn/common/strerror.hpp>
#include <openvpn/buffer/buffer.hpp>
namespace openvpn {
class PersistentFile
{
public:
PersistentFile(const std::string &fn_arg)
: fn(fn_arg)
{
const int f = ::open(fn.c_str(), O_WRONLY | O_CREAT | O_CLOEXEC, S_IRUSR | S_IWUSR);
if (f < 0)
syserr("open");
fd.reset(f);
}
void write(const void *buf, size_t count)
{
const off_t off = ::lseek(fd(), 0, SEEK_SET);
if (off < 0)
syserr("seek");
if (off)
err("unexpected seek");
if (::ftruncate(fd(), 0) < 0)
syserr("truncate");
const ssize_t len = write_retry(fd(), buf, count);
if (len < 0)
syserr("write");
if (static_cast<size_t>(len) != count || len != ::lseek(fd(), 0, SEEK_CUR))
err("incomplete write");
if (::ftruncate(fd(), len) < 0)
syserr("truncate");
}
struct stat stat()
{
struct stat s;
if (::fstat(fd(), &s) < 0)
syserr("fstat");
return s;
}
void write(const Buffer &buf)
{
write(buf.c_data(), buf.size());
}
void write(const std::string &str)
{
write(str.c_str(), str.length());
}
private:
void syserr(const char *type)
{
const int eno = errno;
OPENVPN_THROW_EXCEPTION(fn << " : " << type << " error : " << strerror_str(eno));
}
void err(const char *type)
{
OPENVPN_THROW_EXCEPTION(fn << " : " << type << " error");
}
std::string fn;
ScopedFD fd;
};
} // namespace openvpn
#endif
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